Length of sleep and sleep cycles

Aside from babies and children, who have much greater needs, seven to eight hours is the average amount of sleep required by an adult. This is made up of cycles of REM (Rapid Eye Movement, not the rock band) sleep and non-REM sleep.

However, we don't all have exactly the same needs. Some people can easily get by on 6 hours, whereas other unfortunates feel as if they need 10 hours' sleep to be on form. Judge it on how you feel the next day.

Specialists say there are 3 broad sleeping profiles: sleepers who sleep for a long time, peacefully; those who don't sleep much, badly and wake up exhausted; and those whose sleep is affected by any worry or change in routine.